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Abstract:

This invention relates to rapid drying lacquers that are particularly
useful for automotive OEM refinish applications. The lacquer includes a
novel acrylic triblock copolymer as a replacement material for all or
part of the cellulose acetate butyrate binder component. This invention
is also directed to a process for producing coatings from the rapid
drying lacquers. These lacquers are especially useful in providing chip
and humidity resistant coatings, especially metallic effect coatings,
having excellent adhesion and down flop or metallic effect.

Claims:

1. A triblock copolymer composition, wherein the block copolymer contains
a polymeric A block, a polymeric B block, and a polymeric A' block:
wherein(a) the polymeric A block is of polymerized ethylenically
unsaturated monomer(s) having 1 to 20 carbon atoms, said ethylenically
unsaturated monomer(s) consisting of non-functional monomers and monomers
having one or more interactive functional groups;(b) the polymeric B
block is of a polymerized ethylenically unsaturated monomer(s) having 1
to 20 carbon atoms, said ethylenically unsaturated monomer(s) consisting
essentially of non-functional monomers; and(c) the polymeric A' block is
of polymerized ethylenically unsaturated monomer(s) having 1 to 20 carbon
atoms, said ethylenically unsaturated monomer(s) consisting of
non-functional monomers and monomers having one or more interactive
functional groups; and further whereinthe A and A' blocks have the same
or similar composition and the B block has a different composition from
the A and A' blocks;the A and A' blocks differ from the B block by the
presence, in said A and A' blocks, of one or more interactive functional
groups for the formation of a reversible network, wherein the B-block is
a non-functional block and essentially free of said interactive
functional groups;the interactive functional groups are selected from at
least one of the group consisting of carboxylic acid, hydroxyl, urea,
amide, ethylene oxide groups, and any mixtures thereof; andat least 1% by
weight of the monomers used to form the A and A' blocks contain said
interactive functional groups and at least one of the A and A' blocks
contains one or more groups.

2. (canceled)

3. (canceled)

4. The composition of claim 1, wherein about 5 to 60% by weight of the
monomers used to form the functional blocks A and A' contain said
interactive functional groups.

5. The composition of claim 1, wherein the blocks are linearly attached to
each other in the order given, each at a single terminal point thereof.

6. The composition of claim 4, wherein the block copolymer is made
primarily from acrylic monomers.

7. The composition of claim 1, wherein the ABA' block copolymer is
prepared by a macromonmer approach using cobalt as a catalytic chain
transfer agent.

8. The composition of claim 7, wherein the block copolymer is made
primarily from acrylic or methacrylic monomers or mixtures thereof.

9. The composition of claim 1, wherein the network-forming group comprises
at least one carboxylic acid group.

11. A triblock copolymer composition, wherein the block copolymer has a
weight average molecular weight of about 5,000 to 200,000 and contains a
polymeric A block, a polymeric B block, and a polymeric A' block:
wherein(a) the polymeric A block is of polymerized ethylenically
unsaturated monomer(s) having 1 to 20 carbon atoms, said ethylenically
unsaturated monomer(s) consisting of non-functional monomers and monomers
having one or more interactive functional groups;(b) the polymeric B
block is of a polymerized ethylenically unsaturated monomer(s) having 1
to 20 carbon atoms, said ethylenically unsaturated monomer(s) consisting
essentially of non-functional monomers; and(c) the polymeric A' block is
of polymerized ethylenically unsaturated monomer(s) having 1 to 20 carbon
atoms, said ethylenically unsaturated monomer(s) consisting of
non-functional monomers and monomers having one or more interactive
functional groups; and further wherein the weight average molecular
weight of each block is at least 1,000 andthe A and A' blocks have the
same or similar composition and the B block has a different composition
from the A and A' blocks;the A and A' blocks differ from the B block by
the presence, in said A and A' blocks, of one or more interactive
functional groups for the formation of a reversible network, wherein the
B-block is a non-functional block and essentially free of said
interactive functional groups;the interactive functional groups are
selected from at least one of the group consisting of carboxylic acid,
hydroxyl, urea, amide, ethylene oxide groups, and any mixtures thereof;
andat least 1% by weight of the monomers used to form the A and A' blocks
contain said interactive functional groups and at least one of the A and
A' blocks contains one or more urea groups.

12. (canceled)

13. (canceled)

14. The composition of claim 11, wherein about 5 to 60% by weight of the
monomers used to form the functional blocks A and A' contain said
interactive functional groups.

15. The composition of claim 11, wherein the blocks are linearly attached
to each other in the order given, each at a single terminal point
thereof.

16. The composition of claim 15, wherein the block copolymer is made
primarily from acrylic monomers.

17. The composition of claim 11, wherein the ABA' block copolymer is
prepared by a macromonmer approach using cobalt as a catalytic chain
transfer agent.

18. The composition of claim 17, wherein the block copolymer is made
primarily from acrylic or methacrylic monomers or mixtures thereof.

19. The composition of claim 11, wherein the network-forming group
comprises at least one carboxylic acid group.

Description:

[0001]This invention relates to coating compositions and in particular to
rapid drying lacquer coating compositions that are particularly useful
for automotive refinishing.

BACKGROUND OF THE INVENTION

[0002]To refinish or repair a finish on vehicle, such as a
basecoat/clearcoat finish on automobile or truck bodies, different
fast-drying coating compositions have been developed. A number of
pigmented and clear air-dry acrylic lacquers have been used in the past
to repair basecoat/clearcoat finishes, but none meet the rapid drying
times that are desired, while also meeting today's performance
requirements, such as excellent stone-chip resistance, humidity
resistance, intercoat adhesion, and appearance.

[0003]A key concern to a refinish customer which is typically the vehicle
owner is that the coating in use has excellent durability and
weatherability and an attractive aesthetic appearance.

[0004]Another key concern of the automobile and truck refinish industry is
productivity, i.e., the ability to complete an entire refinish operation
in the least amount of time. To accomplish a high level of productivity,
any coatings applied need to have the ability to dry at ambient or
slightly elevated temperature conditions in a relatively short period of
time. The term "dry" means that the resulting finish is physically dry to
the touch in a relatively short period of time to minimize dirt pick-up,
and, in the case of the basecoat, to allow for the application of the
subsequent clear coat.

[0005]It is also desirable to have quick drying basecoats for additional
reasons. If the applied basecoat composition layer has not dried
sufficiently before the clearcoat composition is applied, then the
application of the clearcoat will disturb the basecoat layer and the
appearance of the basecoat will be adversely affected. For basecoats
containing special effect pigments, e.g., flake pigments such as metallic
and pearlescent flakes, the metallic flake control and metallic
appearance (or downflop) of these basecoats will suffer due to
disturbance of the flake pigment by intermixing of the coating layers at
their interface. "Downflop" refers to a phenomenon associate with
metallic effect coatings wherein the color varies with the angle of view
to provide a three dimensional metallic effect on the surface of the
vehicle.

[0006]Cost and volatile organic solvent content are further concerns in
formulating automotive refinish coating compositions. For example,
cellulose acetate butyrate (CAB) resins have been used to shorten the dry
to handle time and as rheology control additives to enhance metallic
flake control and other properties in refinish basecoats, but coating
compositions containing these CAB material require an undesirable high
amount of organic solvent. In addition, these CAB materials are
relatively expensive and require added steps in the coatings
manufacturing process. The CAB materials are also specialty products that
are not widely manufactured.

[0007]It would be advantageous, therefore, to have a lacquer coating
composition, especially a refinish basecoat lacquer, having a short
tack-free drying time at ambient temperature conditions, good metallic
flake control and appearance, that is less expensive, that has a reduced
amount of regulated emissions, and has the ability to form a finish with
excellent chip and humidity resistance and adhesion. The novel
composition of this invention have the unique combination of properties
desired.

SUMMARY OF THE INVENTION

[0008]This invention is directed to a coating composition, especially to a
lacquer coating composition, comprising a film-forming binder and a
volatile organic liquid carrier, wherein the binder contains, preferably
as a replacement for all or part of the cellulose acetate butyrate
component, a uniquely segmented triblock copolymer. More particularly,
the tri-block copolymer is an ABA'-block copolymer, wherein the ABA'
block copolymer has a weight average molecular weight of about 5,000 to
200,000 and contains a polymeric A block, a polymeric B block, and a
polymeric A' block; wherein:

[0009](a) the polymeric A block is of polymerized ethylenically
unsaturated monomer(s);

[0010](b) the polymeric B block is of a polymerized ethylenically
unsaturated monomer(s); and

[0011](c) the polymeric A' block is of polymerized ethylenically
unsaturated monomer(s); and further wherein

[0012]the polymeric A block, polymeric B block, and polymeric A' block of
the block copolymer, are linearly attached to each other, in the order
given or in reverse order, each at a single point thereof;

[0013]the A and A' blocks have the same or similar composition and the B
block, which is disposed between the A and A' blocks, has a different
composition from the A and A' blocks;

[0014]the A and A' blocks differ from the B block by the presence, on the
A and A' blocks, of one or more functional groups that are capable of
interacting with each other or hydrogen (H) bonding with each other for
the formation of a reversible network; and

[0015]the functional groups are selected from at least one of the group
consisting of carboxylic acid, hydroxyl, urea, amide, and ethylene oxide
groups, or mixtures of any of the above.

[0016]Preferably, the dissimilar B block disposed between the A' and A'
blocks is a non-functional block, essentially free of functional groups.

[0017]The lacquer composition is most suited for use as a pigmented
basecoat lacquer in automotive refinish applications, on top of which a
transparent (clear) topcoat is applied.

[0018]While this composition is preferably used as a lacquer coating which
dries via solvent evaporation absent any substantial crosslinking
occurring, it optionally may contain a polyisocyanate crosslinking agent
for further improved film properties.

[0019]This invention is further directed to a process for producing a
coating on the surface of a substrate, such as a vehicle body or part
thereof, wherein the process comprises:

[0020]applying a layer of a lacquer coating composition on the substrate
surface, which may be previously primed or sealed or otherwise treated,
the lacquer comprising the aforesaid composition; and

[0021]drying the layer, preferably at ambient conditions, to form a
coating on the surface of the substrate, on top of which a clearcoat can
be applied.

[0022]Also included within the scope of this invention is the triblock
copolymer composition formulated for use in the lacquer and a substrate
coated with the lacquer coating composition disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

[0023]As used herein:

[0024]"Lacquer" means a coating composition that dries primarily by
solvent evaporation and does not require crosslinking to form a film
having the desired physical properties.

[0025]All "molecular weights" are determined by gel permeation
chromatography (GPC) using polystyrene as the standard.

[0026]"Tg" (glass transition temperature) of the polymer can be measured
by differential scanning calorimetry (DSC) or it can be calculated as
described by Fox in Bull. Amer. Physics Soc., 1, 3, page 123 (1956).

[0027]"Acrylic polymer" means a polymer comprised of polymerized
"(meth)acrylate(s)" which mean acrylates and methacrylates, optionally
copolymerized with other ethylenically unsaturated monomers, such as
acrylamides, methacrylamides, acrylonitriles, methacrylonitriles, and
vinyl aromatics such as styrene.

[0028]The present invention is directed to a pigmented or clear air-dry
lacquer, preferably an acrylic lacquer, suited for various coating
processes, such as automotive OEM and automotive refinish. The novel
lacquer is particularly well suited for use in automotive refinishing,
particularly as a colored refinish basecoat used for repairing or
refinishing colored basecoat/clearcoat finishes on auto and truck bodies.

[0029]Advantageously, the air-dry lacquer coating compositions formed have
excellent physical properties, such as excellent chip and humidity
resistance and intercoat adhesion, without sacrificing desired fast dry
properties at ambient temperatures and overall appearance, such as DOI
(distinctness of image) and HOB (head on brightness).

[0030]The lacquer coating composition of this invention preferably
contains about 5 to 90% by weight, based on the weight of the coating
composition, of a film-forming binder containing an ABA' triblock
polymer, preferably an acrylic polymer, as a replacement for all or part
of the cellulose acetate butyrate (CAB) resin in the binder and
correspondingly about 10 to 95% by weight, based on the weight of the
coating composition, of a volatile organic liquid carrier and optionally
contains pigments in a pigment to binder weight ratio of about 0.1/100 to
200/100.

ABA' Triblock Copolymer

[0031]The ABA' triblock copolymer, which also forms part of this
invention, used herein as part of the film forming binder has a weight
average molecular weight of 5,000-200,000 and preferably about
10,000-100,000, and more preferably in a range from about 15,000-80,000.

[0032]The A and A' blocks of the ABA' block polymer have the same or
similar composition and both have at least one interactive functional
group described below.

[0033]By the "same" composition, it is meant that the A and A' blocks are
prepared from the same set of monomers, same monomer ratios, and contain
the same type interactive functional groups in the same concentration. By
"similar" composition, it is meant that both the A and A' blocks still
contain at least one interactive functional group and serve the same
network-forming function, but the monomer set, monomer ratio, type of
functional groups, and/or concentration of functional groups may be
different in each block.

[0034]As to the B block, this block is preferably disposed between the A
and A' blocks and preferably is a non-functional block that contains
mostly polymerized non-functional monomers.

[0035]As indicated above, the A and A' blocks differ from the B block by
presence of interactive functional groups. The functional groups used in
the A and A' blocks are capable of interacting/H-bonding with each other
for the formation of a network that is sensitive to shear force,
temperature, or pH. The B block is preferably essentially free of
functional groups.

[0036]The interactive/H-bonding functional groups are preferably selected
from at least one of the following groups 1 to 6:

[0037]1) Hydroxyl groups (e.g., primary or secondary hydroxyl)

[0038]2) Acid groups (e.g., carboxyl groups);

[0039]3) Urea;

[0040]4) Amide;

[0041]5) Ethylene Oxide; or

[0042]6) Mixtures of any of the above.

[0043]The size of each block (or polymeric segment) will vary depending on
the final properties desired. However, each block should be substantially
linear and contain on average at least 3 units of monomers and have a
number average molecular weight greater than 300. In preferred
embodiments, the number of monomers within a single block is about 10 or
more. Also in preferred embodiments, the weight average molecular weight
of each block is at least 1,000, generally in a range from about
1,000-40,000, more preferably from about 1,500-30,000.

[0044]The concentration of and type of interactive functional groups on
the blocks will also vary depending on the particular attribute desired;
however, the concentration of interactive groups should be such that at
least 1% to 100%, more preferably at least 5 to 60% by weight, of the
monomers used to form that given block have interactive functional
groups.

[0045]In the present invention, it is particularly useful to concentrate
the interactive functional groups on the outer blocks (or A and A'
blocks), with the remaining inner block (or B block) containing
essentially no functional groups. This construction particularly
facilitates the network formation attribute desired. By "essentially no"
functional groups or "essentially free" of functional groups, it is meant
that the B block should contain less than 1% by weight, preferably zero
percent by weight, of functionalized monomers, based on the total weight
of the block copolymer.

[0046]As will be appreciated by those skilled in the art, it may also
sometimes be desirable to have crosslinkable groups, such as hydroxyl
groups (which can serve a dual function of H-bonding and crosslinking) or
amine groups, on at least one of the blocks, preferably the outer
block(s) for potential crosslinking with other binder components, for
further improved film properties.

[0047]The ABA' triblock copolymer that can be used herein, as part of the
binder, to replace the CAB polymer can be prepared by living
polymerization methods such as anionic polymerization, group transfer
polymerization (GTP), nitroxide-mediated free radical polymerization,
atom transfer radical polymerization (ATRP), or reversible
addition-fragmentation chain transfer (RAFT) polymerization techniques.
Preferably, the polymer is prepared by the catalytic chain transfer
approach for making the triblock copolymers of this invention.

[0048]Most of the other living polymerization approaches mentioned above
involve special and costly raw materials including special initiating
systems and high purity monomers. Some of them have to be carried out
under extreme conditions such as low moisture or low temperature.
Furthermore, some of these methods are sensitive to the active hydrogen
groups on the monomers that are key to our invention such as the hydroxyl
and carboxylic acid groups. These groups would have to be chemically
protected during the polymerization and recovered in a subsequent step.
In addition, some of the initiating systems bring undesirable color,
odor, metal complexes, or potentially corrosive halides into the product.
Extra steps would be required to remove them. In the preferred method,
the catalyst is used at extremely low concentration and has minimum
impact on the quality of the product, and the synthesis can be
conveniently accomplished in a one-pot process.

[0049]In the catalytic chain transfer agent approach or "macromonomer"
approach, the triblock copolymers are most conveniently prepared by a
multi-step free radical polymerization process. Such a process is taught,
for example in U.S. Pat. No. 6,291,620 to Moad et al., hereby
incorporated by reference in its entirety.

[0050]In the first step of the macromonomer process, the first or outer
block A of the triblock copolymer is formed using a free radical
polymerization method wherein ethylenically unsaturated monomers or
monomer mixtures chosen for this block are polymerized in the presence of
cobalt catalytic chain transfer agents or other transfer agents that are
capable of terminating the free radical polymer chain and forming a
"macromonomer" with a terminal polymerizable double bond in the process.
The polymerization is preferably carried out at elevated temperature in
an organic solvent or solvent blend using a conventional free radical
initiator and Co (II) or (III) chain transfer agent.

[0051]Once the first macromonomer block having the desired molecular
weight and conversion is formed, the cobalt chain transfer agent is
deactivated by adding a small amount of oxidizing agent such as
hydroperoxide. The unsaturated monomers or monomer mixtures chosen for
the next block B are then polymerized in the presence of the first block
and more initiator. This step, which can be referred to as a macromonomer
step-growth process, is likewise carried out at elevated temperature in
an organic solvent or solvent blend using a conventional polymerization
initiator. Polymerization is continued until a macromonomer is formed of
the desired molecular weight and desired conversion of the second block
into a diblock macromonomer. The third block A' or other outer block of
the triblock copolymer is then added onto it in the same manner to
produce the triblock copolymers of this invention.

[0052]Preferred cobalt chain transfer agents are described in U.S. Pat.
Nos. 4,680,352 to Janowicz et al and 4,722,984 to Janowicz, hereby
incorporated by reference in their entirety. Most preferred cobalt chain
transfer agents are pentacyano cobaltate (II),
diaquabis(borondifluorodimethylglyoximato) cobaltate (II), and
diaquabis(borondifluorophenylglyoximato) cobaltate (II). Typically these
chain transfer agents are used at concentrations of about 2-5000 ppm
based on the total weight of the monomer depending upon the particular
monomers being polymerized and the desired molecular weight. By using
such concentrations, macromonomers having the desired molecular weight
can be conveniently prepared.

[0053]To make distinct blocks, the growth of each block needs to occur to
high conversion. Conversions are determined by size exclusion
chromatography (SEC) via integration of polymer to monomer peak. For UV
detection, the polymer response factor must be determined for each
polymer/monomer polymerization mixture. Typical conversions can be 50% to
100% for each block. Intermediate conversion can lead to block copolymers
with a transitioning (or tapering) segment where the monomer composition
gradually changes to that of the following block as the addition of the
monomer or monomer mixture of the next block continues. This may affect
polymer properties such as phase separation, thermal behavior and
mechanical modulus and can be intentionally exploited to drive properties
for specific applications. This may be achieved by intentionally
terminating the polymerization when a desired level of conversion (e.g.,
>80%) is reached by stopping the addition of the initiators or
immediately starting the addition of the monomer or monomer mixture of
the next block along with the initiator.

[0054]Typical solvents that can be used to form the triblock copolymer are
alcohols, such as methanol, ethanol, n-propanol, and isopropanol;
ketones, such as acetone, butanone, pentanone, and hexanone; alkyl esters
of acetic, propionic, and butyric acids, such as ethyl acetate, butyl
acetate, and amyl acetate; ethers, such as tetrahydrofuran, diethyl
ether, and ethylene glycol and polyethylene glycol monoalkyl and dialkyl
ethers such as cellosolves and carbitols; and, glycols such as ethylene
glycol and propylene glycol; and mixtures thereof.

[0055]Any of the commonly used azo or peroxide type polymerization
initiators can be used for preparation of the macromonomer or the
triblock copolymer provided it has solubility in the solution of the
solvents and the monomer mixture, and has an appropriate half life at the
temperature of polymerization. "Appropriate half life" as used herein is
a half-life of about 10 minutes to 4 hours. Most preferred are azo type
initiators such as 2,2'-azobis(isobutyronitrile),
2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(methylbutyronitrile),
and 1,1'-azobis(cyanocyclohexane). Examples of peroxy based initiators
are benzoyl peroxide, lauroyl peroxide, t-butyl peroxypivalate, t-butyl
peroctoate which may also be used, provided they do not adversely react
with the chain transfer agents under the reaction conditions for
macromonomers.

[0056]Any of the conventional acrylic monomers and optionally other
ethylenically unsaturated monomers or monomer mixtures can be used to
form the individual A, B and A' blocks of the triblock copolymer of this
invention. Depending on the preparation methods, certain monomers or
monomer mixtures will work better than the others. For the preferred
method of preparation for this invention, the "macromonomer" approach,
methacrylate monomers must be used. Specifically, each individual block
must contain at least 70 mole percent of a methacrylate monomer or
methacrylate monomer mixtures. More preferred is a composition containing
at least 90 mole percent of a methacrylate monomer or methacrylate
monomer mixtures. The other comonomers may be of the type of acrylate,
acrylamide, methacrylamide, vinyl aromatics such as styrene, and vinyl
esters.

[0057]For example, monomers that may be polymerized using the methods of
this invention include at least one monomer selected from the group
consisting of unsubstituted or substituted alkyl acrylates, such as those
having 1-20 carbon atoms in the alkyl group, alkyl methacrylate such as
those having 1-20 carbon atoms in the alkyl group, cycloaliphatic
acrylates, cycloaliphatic methacrylates, aryl acrylates, aryl
methacrylates, other ethylenically unsaturated monomers such as
acrylonitriles, methacrylonitriles, acrylamides, methacrylamides,
N-alkylacrylamides, N-alkylmethacrylamides, N,N-dialkylacrylamides,
N,N-dialkylmethacrylamides, vinyl aromatics such as styrene, and
combinations thereof. Functionalized versions of these monomers and their
relative concentrations are especially useful in differentiating the
blocks, as will be discussed further hereinbelow.

[0058]In the present invention, as mentioned above, preferably the two
outer blocks, A and A', contain a functional group, referred to herein as
an interactive or H-bonding group, for network formation and better
metallic flake control. This group will lead to the formation of a
network that is connected by physical forces and is sensitive to shear
force, temperature, or pH. This type of system is useful for its
rheological properties such as the thixotropic behavior and parallel
metallic flake orientation. Groups capable of hydrogen bonding in
particular, which will be discussed further hereinbelow, may be
advantageously employed for this purpose.

[0059]This group will vary depending on the nature of the other binder
components present in the lacquer coating; however, carboxylic acid and
other acid groups as are listed below are generally preferred.

[0062]To introduce interactive/H-bonding acid groups into the triblock
copolymer at the appropriate blocks, acid-functional monomers can be
used. Carboxylic acid functional monomers are generally preferred for
better compatibility with other binder components in the lacquer coating
composition. The most commonly used carboxyl acid group containing
monomers are methacrylic acid and acrylic acid. Others include
beta-carboxyethyl acrylate, vinyl benzoic acid (all isomers),
alpha-methylvinyl benzoic acid (all isomers), and the diacids such as
maleic acid, fumaric acid, itaconic acid, and their anhydride form that
can be hydrolyzed to the carboxylic acid groups after the polymers are
made. Of course, a low level of other types of acid groups, such as
sulfonic acid or phosphoric acid may be used.

[0063]Useful amide functional monomers which can be used to introduce
interactive/H-bonding amide groups into the polymer include acrylamides
and methacrylamides and other vinyl monomers containing either a cyclic
or acyclic amide group.

[0064]Examples of acrylamide or methacrylamide monomers are represented by
the formula

##STR00001##

[0065]where R1 and R2 are each independently selected from the
group consisting of hydrogen, alkyl group, aryl group, arylalkyl group,
and alkylaryl group having 1 to 20 carbon atoms, and optionally
containing one or more substituents that do not interfere with the
polymerization process. Such substituents may include alkyl, hydroxy,
amino, ester, acid, acyloxy, amide, nitrile, halogen, alkoxy, etc. Useful
examples include methacrylamides such as N-methylmethacrylamide,
N-ethylmethacrylamide, N-octylmethacrylamide, N-dodecylmethacrylamide,
N-(isobutoxymethyl) methacrylamide, N-phenylmethacrylamide,
N-benzylmethacrylamide, N,N-dimethylmethacrylamide, and the like; and
acrylamides such as N-methyl acrylamide, N-ethylacrylamide,
N-t-butylacrylamide, N-(isobutoxymethyl) acrylamide,
N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-dibutyl acrylamide,
and the like.

[0066]Examples of vinyl monomers that can be used to introduce cyclic
amide groups into the copolymer include acrylic, methacrylic, acrylamide,
methacrylamide, and some other vinyl monomers. The acrylic, methacrylic,
acrylamide and methacrylamide monomers are represented by formula

##STR00002##

[0067]where Y is O or N, R3 is selected from the group consisting of
alkyl group, aryl group, arylalkyl group, and alkylaryl group having 1 to
20 carbon atoms and may contain substituents which do not interfere with
polymerization such as hydroxy, amino, ester, acid, acyloxy, amide,
nitrile, halogen, alkoxy, etc., R4 does not exist when Y is O but
when Y is N, R4 is selected from the group consisting of hydrogen,
alkyl group, aryl group, arylalkyl group, and alkylaryl group having 1 to
20 carbon atoms and may contain substituents which do not interfere with
polymerization such as hydroxy, amino, ester, acid, acyloxy, amide,
nitrile, halogen, alkoxy, etc., and Z is a radical center connected to
structure (1) or (2) below.

[0068]Other vinyl monomers which can also be used to introduce the
interactive cyclic amide groups are represented by formula

##STR00003##

where R5 is selected from the group consisting of alkyl group, aryl
group, arylalkyl group, and alkylaryl group having 0 to 20 carbon atoms
and may contain substituents which do not interfere with polymerization
such as hydroxy, amino, ester, acid, acyloxy, amide, nitrile, halogen,
alkoxy, etc., and Z is a radical center connected to structure (1) or (2)
below. The most useful example is N-vinyl-2-pyrrolidinone.

[0069]Structures (1) and (2), respectively, are represented by

##STR00004##

[0070]where n=3-7, preferably 3-5, m=0-3, X is a substituent on the cyclic
structure and may be selected from the group consisting of alkyl group,
aryl group, arylalkyl group, alkylaryl group, and heterocyclic group
having 1 to 20 carbon atoms, and may contain substituents which do not
interfere with polymerization such as hydroxy, amino, ester, acid,
acyloxy, amide, nitrile, halogen, alkoxy, etc., R is selected from the
group consisting of hydrogen, alkyl group, aryl group, arylalkyl group,
and alkylaryl group having 1 to 20 carbon atoms, and may contain
substituents which do not interfere with polymerization such as hydroxy,
amino, ester, acid, acyloxy, amide, nitrile, halogen, alkoxy, etc., and Z
is a radical center connected to the vinyl monomer structures referenced
above. Examples of the heterocyclic group include triazole, triazine,
imidazole, piperazine, pyridine, pyrimidine, and the like.

[0071]Useful urea functional monomers which can be used to introduce
interactive/H-bonding urea groups into the polymer include acrylates
methacrylates, acrylamides, methacrylamides and other vinyl monomers
containing either a cyclic or a linear/acyclic urea group.

[0072]The urea containing acrylic, methacrylic, acrylamide, and
methacrylamide monomers are represented by the general formula of

##STR00005##

[0073]where Y, R3 and R4 are as described above, and Z' is a
radical center connected to structure (3) below for a linear or acyclic
urea group, or (4) or (5) below for a cyclic urea group.

[0074]Other vinyl monomers which can also be used to introduce either
acyclic or cyclic urea group are represented by the general formula of

##STR00006##

[0075]where R5 is as described above, and Z' is a radical center
connected to structure (3) below for a linear or acyclic urea group, or
(4) or (5) for a cyclic urea group.

[0076]Structure (3), (4), and (5), respectively, are represented by

##STR00007##

[0077]where n=0-5, preferably 2-5, m=0-3, X is a substituent on the cyclic
structure and may be selected from the group consisting of alkyl group,
aryl group, arylalkyl group, alkylaryl group, and heterocyclic group
having 1 to 20 carbon atoms, and may contain substituents which do not
interfere with polymerization such as hydroxy, amino, ester, acid,
acyloxy, amide, nitrile, halogen, alkoxy, etc., each R is independently
selected from the group consisting of hydrogen, alkyl group, aryl group,
arylalkyl group, alkylaryl group, and heterocyclic group having 1 to 20
carbon atoms, and may contain substituents which do not interfere with
polymerization such as hydroxy, amino, ester, acid, acyloxy, amide,
nitrile, halogen, alkoxy, etc., and Z' is a radical center connected to
the vinyl monomer structures referenced above. Examples of the
heterocyclic group include triazole, triazine, imidazole, piperazine,
pyridine, pyrimidine, and the like. The cyclic urea structure may also
contain other heteroatoms such as O, S, N(R), or groups such as C(O),
S(O)2 or unsaturated double bonds, especially when n is 0 or 1.
Examples of such structures include urazole, uracil, cytosine, and
thymine.

[0078]Typical examples of ethylenically unsaturated urea containing
monomers are described in U.S. Pat. Nos. 5,030,726 and 5,045,616, hereby
incorporated by reference. Preferred monomers of this type are the
acrylate, methacrylate, acrylamide or methacrylamide derivatives of
2-hydroxyethylene urea (HEEU), or 2-aminoethylethylene urea (AEEU). The
most preferred monomers of this type that are commercially available
include N-(2-methacryloyloxyethyl)ethylene urea and
methacrylamidoethylethylene urea. Other examples of urea containing
monomers can be obtained by reacting an ethylenically unsaturated monomer
having an isocyanato group such as dimethyl m-isopropenylbenzyl
isocyanate (m-TMI) or 2-isocyanatoethyl methacrylate (ICEMA) with a
hydroxyl or amino compound having a linear or a cyclic urea group such as
HEEU or AEEU. In these examples the urea group is linked to the monomer
through a urethane or another urea group.

[0079]The ethylene oxide groups are capable of hydrogen-bonding with other
functional groups that are also desirable for the polymer of this
invention such as carboxylic acid. They can be conveniently introduced
with the monomers of the general formula of

CH2═C(R6)(C(O)OXn(CH2CH2O)m)--R7

[0080]wherein n=0 or 1; when n=1, X is an alkyl, aryl, or alkaryl
diradical connecting group of 1-10 carbon atoms; m=2-100, R6 is H or
CH3, and R7 is an alkyl group of 1-10 carbon atoms. Useful
examples of such comonomers include 2-(2-methoxyethoxy)ethyl acrylate,
2-(2-methoxyethoxy)ethyl methacrylate, ethoxytriethyleneglycol
methacrylate, methoxy polyethyleneglycol (molecular weight of 200-100)
monomethacrylate, polyethyleneglycol (molecular weight 200-1000)
monomethacrylate.

[0081]As indicated above, the choice of monomers and monomer mixtures for
each block, the block size, overall ratios of monomers used to form the
blocks, and molecular weights, and nature of each block will vary so as
to provide the particular attribute desired for a particular application.

[0083]It should be understood that the polymer can be made starting from
either end. For instance, an A'BA (reverse of ABA') block polymer also
can be formed and is part of this invention. In forming a A'BA block
polymer, the A' block is first made using the same procedure as above and
then the monomers for the B block are added and after the B block is
formed the monomers for the A block are added and polymerized.

[0084]The novel coating composition of the present invention generally
contains as part of the binder, in the range of about 1 to 80% by weight,
preferably about 5 to 60%, and even more preferably in the range of about
10 to 40% by weight of this CAB replacement polymer, all weight
percentages being based on the total weight of the binder.

Other Binder Materials

[0085]In addition to the triblock copolymer described above, the coating
composition can also include, as part of the binder, 0 to 98% by weight,
preferably in the range of 20 to 95%, and even more preferably from 30 to
90% by weight of an acrylic polymer, polyester, alkyd resin, acrylic
alkyd resin, cellulose acetate butyrate, an iminated acrylic polymer,
ethylene vinyl acetate co-polymer, nitrocellulose, plasticizer or a
combination thereof, all weight percentages being based on the total
weight of the binder.

[0086]Useful acrylic polymers are conventionally polymerized from a
monomer mixture that can include one or more of the following monomers:
an alkyl acrylate; an alkyl methacrylate; a hydroxy alkyl acrylate, a
hydroxy alkyl methacrylate; acrylic acid; methacrylic acid; styrene;
alkyl amino alkyl acrylate; and alkyl amino alkyl methacrylate, and
mixtures thereof; and one or more of the following drying oils: vinyl
oxazoline drying oil esters of linseed oil fatty acids, tall oil fatty
acids, and tung oil fatty acids.

[0088]Useful polyesters include the esterification product of an aliphatic
or aromatic dicarboxylic acid, a polyol, a diol, an aromatic or aliphatic
cyclic anhydride and a cyclic alcohol. One such polyester is the
esterification product of adipic acid, trimethylol propane, hexanediol,
hexahydrophathalic anhydride and cyclohexane dimethylol.

[0089]Other polyesters that are useful in the present invention are
branched copolyester polyols. One particularly preferred branched
polyester polyol is the esterification product of dimethylolpropionic
acid, pentaerythritol and epsilon-caprolactone. These branched
copolyester polyols and the preparation thereof are further described in
WO 03/070843 published Aug. 28, 2003, which is hereby incorporated by
reference.

[0090]Suitable cellulose acetate butyrates, which may still be used, if
desired, are supplied by Eastman Chemical Co., Kingsport, Tenn. under the
trade names CAB-381-20 and CAB-531-1. These materials may be used in an
amount of 0.1 to 20% by weight based on the weight of the binder.
Preferably, however, the lacquers of this invention are free or
essentially free of these materials, especially the high molecular
weight, high hydroxyl number CAB resins like CAB-381-20.

[0092]Suitable nitrocellulose resins preferably have a viscosity of about
1/2-6 seconds. Preferably, a blend of nitrocellulose resins is used.
Optionally, the lacquer can contain ester gum and castor oil.

[0093]Suitable alkyd resins are the esterification products of a drying
oil fatty acid, such as linseed oil and tall oil fatty acid, dehydrated
castor oil, a polyhydric alcohol, a dicarboxylic acid and an aromatic
monocarboxylic acid. One preferred alkyd resin is a reaction product of
an acrylic polymer and an alkyd resin.

[0096]If the lacquer is to be used as a clearcoat for the exterior of
automobiles and trucks, about 0.1 to 5% by weight, based on the weight of
the total weight of the binder, of an ultraviolet light stabilizer or a
combination of ultraviolet light stabilizers and absorbers can be added
to improve the weatherability of the composition. These stabilizers
include ultraviolet light absorbers, screeners, quenchers and specific
hindered amine light stabilizers. Also, about 0.1 to 5% by weight, based
on the total weight of the binder, of an antioxidant can be added. Most
of the foregoing stabilizers are supplied by Ciba Specialty Chemicals,
Tarrytown, N.Y.

[0097]Additional details of the foregoing additives are provided in U.S.
Pat. Nos. 3,585,160, 4,242,243, 4,692,481, and US Re 31,309, which are
hereby incorporated by reference.

Pigments

[0098]If desired, the novel composition can be pigmented to form a colored
mono coat, basecoat, primer or primer surfacer. Generally, pigments are
used in a pigment to binder weight ratio (P/B) of 0.1/100 to 200/100;
preferably, for base coats in a P/B of 1/100 to 50/100. If used as primer
or primer surfacer higher levels of pigment are used, e.g., 50/100 to
200/100. The pigments can be added using conventional techniques, such as
sand-grinding, ball milling, attritor grinding, two roll milling to
disperse the pigments. The mill base is blended with the film-forming
constituents.

[0099]Any of the conventional pigments used in coating compositions can be
utilized in the composition such as the following: metallic oxides, metal
hydroxide, metal flakes, chromates, such as lead chromate, sulfides,
sulfates, carbonates, carbon black, silica, talc, china clay,
phthalocyanine blues and greens, organo reds, organo maroons, pearlescent
pigments and other organic pigments and dyes. If desired, chromate-free
pigments, such as barium metaborate, zinc phosphate, aluminum
triphosphate and mixtures thereof, can also be used.

[0101]The lacquer of the present invention can further, and typically
does, contain at least one volatile organic solvent as the liquid carrier
to disperse and/or dilute the above ingredients and form a coating
composition having the desired properties. The solvent or solvent blends
are typically selected from the group consisting of aromatic
hydrocarbons, such as, petroleum naphtha or xylenes; ketones, such as,
methyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone or
acetone; esters, such as butyl acetate or hexyl acetate; glycol ether
esters, such as, propylene glycol monomethyl ether acetate; and alcohols,
such as isopropanol and butanol. The amount of organic solvent added
depends upon the desired solids level, desired rheological (e.g., spray)
properties, as well as the desired amount of VOC of the lacquer.

[0102]The total solids level of the coating of the present invention can
vary in the range of from 5 to 95%, preferably in the range of from 7 to
80% and more preferably in the range of from 10 to 60%, all percentages
being based on the total weight of the coating composition.

Optional Crosslinking Component

[0103]If the novel composition is used as a clear coating composition, a
crosslinking component is generally known to provide the improved level
of durability and weatherability required for automotive and truck
topcoats. Typically, polyisocyanates are used as the crosslinking agents.
Suitable polyisocyanate has on average 2 to 10, alternately 2.5 to 8 and
further alternately 3 to 8 isocyanate functionalities. Typically the
coating composition has, in the binder, a ratio of isocyanate groups on
the polyisocyanate in the crosslinking component to crosslinkable groups
(e.g., hydroxyl and/or amine groups) of the branched acrylic polymer
ranges from 0.25/1 to 3/1, alternately from 0.8/1 to 2/1, further
alternately from 1/1 to 1.8/1.

[0104]Examples of suitable polyisocyanates include any of the
conventionally used aromatic, aliphatic or cycloaliphatic di-, tri- or
tetra-isocyanates, including polyisocyanates having isocyanurate
structural units, such as, the isocyanurate of hexamethylene diisocyanate
and isocyanurate of isophorone diisocyanate; the adduct of 2 molecules of
a diisocyanate, such as, hexamethylene diisocyanate; uretidiones of
hexamethylene diisocyanate; uretidiones of isophorone

[0105]diisocyanate or isophorone diisocyanate; isocyanurate of
meta-tetramethylxylylene diisocyanate; and a diol such as, ethylene
glycol.

[0106]Polyisocyanates functional adducts having isocyanaurate structural
units can also be used, for example, the adduct of 2 molecules of a
diisocyanate, such as, hexamethylene diisocyanate or isophorone
diisocyanate, and a diol such as ethylene glycol; the adduct of 3
molecules of hexamethylene diisocyanate and 1 molecule of water
(available under the trademark Desmodur® N from Bayer Corporation of
Pittsburgh, Pa.); the adduct of 1 molecule of trimethylol propane and 3
molecules of toluene diisocyanate (available under the trademark
Desmodur® L from Bayer Corporation); the adduct of 1 molecule of
trimethylol propane and 3 molecules of isophorone diisocyanate or
compounds, such as 1,3,5-triisocyanato benzene and
2,4,6-triisocyanatotoluene; and the adduct of 1 molecule of
pentaerythritol and 4 molecules of toluene diisocyanate.

[0107]The coating composition containing a crosslinking component
preferably includes one or more catalysts to enhance crosslinking of the
components on curing. Generally, the coating composition includes in the
range of from 0.01 to 5% by weight, based on the total weight of the
binder.

[0108]Suitable catalysts for polyisocyanate can include one or more tin
compounds, tertiary amines or a combination thereof. Suitable tin
compounds include dibutyl tin dilaurate, dibutyl tin diacetate, stannous
octoate, and dibutyl tin oxide. Dibutyl tin dilaurate is preferred.
Suitable tertiary amines include triethylene diamine. One commercially
available catalyst that can be used is Fastcat® 4202 dibutyl tin
dilaurate sold by Elf-Atochem North America, Inc. Philadelphia, Pa.
Carboxylic acids, such as acetic acid, may be used in conjunction with
the above catalysts to improve the viscosity stability of two component
coatings.

Application

[0109]In use, a layer of the novel composition is typically applied to a
substrate by conventional techniques, such as, spraying, electrostatic
spraying, roller coating, dipping or brushing. Spraying and electrostatic
spraying are preferred application methods. When used as a pigmented
coating composition, e.g., as a basecoat or a pigmented top coat, the
coating thickness can range from 10 to 85 micrometers, preferably from 12
to 50 micrometers and when used as a primer, the coating thickness can
range from 10 to 200 micrometers, preferably from 12 to 100 micrometers.
When used as a clear coating, the thickness is in the range of from 25
micrometers to 100 micrometers. The coating composition can be dried at
ambient temperatures or can be dried upon application for about 2 to 60
minutes at elevated drying temperatures ranging from about 50° C.
to 100° C.

[0110]In a typical clearcoat/basecoat application, a layer of conventional
clear coating composition is applied over the basecoat of the novel
composition of this invention by the above conventional techniques, such
as, spraying or electrostatic spraying. Generally, a layer of the
basecoat is flashed for 1 minute to two hours under ambient or elevated
temperatures before the application of the clear coating composition or
dried at elevated temperatures shown above. Suitable clear coating
compositions can include two-pack isocyanate crosslinked compositions,
such as 72200S ChromaPremier® Productive Clear blended with an
activator, such as 12305S ChromaPremier®Activator, or 3480S Low VOC
Clear composition activated with 194S Imron Select® Activator.
Isocyanate free crosslinked clear coating compositions, such as 1780S
Iso-Free Clearcoat activated with 1782S Converter and blended with 1775S
Mid-Temp Reducer are also suitable. Suitable clear lacquers can include
480S Low VOC Ready to Spray Clear composition. All the foregoing clear
coating compositions are supplied by DuPont (E.I. Dupont de Nemours and
Company, Wilmington, Del.).

[0111]If the coating composition of the present invention contains a
crosslinking agent, such as a polyisocyanate, the coating composition can
be supplied in the form of a two-pack coating composition in which the
first-pack includes the branched acrylic polymer and the second pack
includes the crosslinking component, e.g., a polyisocyanate. Generally,
the first and the second packs are stored in separate containers and
mixed before use. The containers are preferably sealed air tight to
prevent degradation during storage. The mixing may be done, for example,
in a mixing nozzle or in a container. When the crosslinking component
contains, e.g., a polyisocyanate, the curing step can take place under
ambient conditions, or if desired, it can take place at elevated baking
temperatures.

[0112]For a two pack coating composition, the two packs are mixed just
prior to use or 5 to 30 minutes before use to form a potmix. A layer of
the potmix is typically applied to a substrate by the above conventional
techniques. If used as a clear coating, a layer is applied over a metal
substrate, such as, automotive body, which is often pre-coated with other
coating layers, such as, an electrocoat primer, primer surfacer and a
basecoat. The two-pack coating composition may be dried and cured at
ambient temperatures or may be baked upon application for 10 to 60
minutes at baking temperatures ranging from 80° C. to 160°
C. The mixture can also contain pigments and can be applied as a mono
coat or a basecoat layer over a primed substrate or as a primer layer.

[0113]The coating composition of the present invention is suitable for
providing coatings on variety of substrates. Typical substrates, which
may or may not be previously primed or sealed, for applying the coating
composition of the present invention include automobile bodies, any and
all items manufactured and painted by automobile sub-suppliers, frame
rails, commercial trucks and truck bodies, including but not limited to
beverage bottles, utility bodies, ready mix concrete delivery vehicle
bodies, waste hauling vehicle bodies, and fire and emergency vehicle
bodies, as well as any potential attachments or components to such truck
bodies, buses, farm and construction equipment, truck caps and covers,
commercial trailers, consumer trailers, recreational vehicles, including
but not limited to, motor homes, campers, conversion vans, vans, pleasure
vehicles, pleasure craft snow mobiles, all terrain vehicles, personal
watercraft, motorcycles, bicycles, boats, and aircraft. The substrate
further includes industrial and commercial new construction and
maintenance thereof; cement and wood floors; walls of commercial and
residential structures, such office buildings and homes; amusement park
equipment; concrete surfaces, such as parking lots and drive ways;
asphalt and concrete road surface, wood substrates, marine surfaces;
outdoor structures, such as bridges, towers; coil coating;

[0115]The novel compositions of this invention are also suitable as clear
or pigmented coatings in industrial and maintenance coating applications.

[0116]These and other features and advantages of the present invention
will be more readily understood, by those of ordinary skill in the art
from the following examples. In the examples, all parts and percentages
are on a weight basis unless otherwise noted.

EXAMPLES

[0117]The following ABA' triblock copolymer were prepared from the
following macromonomers and then used to form lacquer coating
compositions.

Example 1

Preparation of MAA/HEMA/ETEGMA Macromonomer, 60/20/20% by weight

[0118]This example illustrates the preparation of a macromonomer with
carboxyl groups, primary hydroxyl groups, and polyethylene oxide groups
that are capable of forming hydrogen bonds and can be used to form the A
block (outer block) of a triblock copolymer of this invention. A 5-liter
flask was equipped with a thermometer, stirrer, additional funnels,
heating mantel, reflux condenser and a means of maintaining a nitrogen
blanket over the reactants. The flask was held under nitrogen positive
pressure and the following ingredients were employed.

[0119]Portion 1 mixture was charged to the flask and the mixture was
heated to reflux temperature and refluxed for about 20 minutes. Portion 2
was prepared by dissolving the cobalt catalyst completely. Portion 3 was
added to Portion 2 and agitated to dissolve the initiator. The mixture of
Portion 2 and Portion 3 was fed to the flask over 210 minutes while
Portion 4 was simultaneously fed to the flask over 180 minutes, and the
reaction mixture was held at reflux temperature throughout the course of
additions. Reflux was continued for another 1.5 hours and the solution
was cooled to room temperature and filled out.

[0120]The resulting macromonomer solution was a light yellow clear polymer
solution and had a solid content of about 36.2% and a Gardner-Holtz
viscosity of P. The macromonomer had a 6,390 Mw and 3,805 Mn after the
carboxyl groups were protected by methyl groups to facilitate the GPC
analysis.

Example 2

Preparation of an AB Diblock Macromonomer BMA/MMA//MAA/HEMA/ETEGMA,
45/30//15/5/5 by weight

[0121]This example shows the preparation of a diblock macromonomer where
the B block (center block) has no specific functional groups and the A
block (one of the terminal block) contains carboxyl groups, primary
hydroxyl groups, and polyethylene oxide groups from the macromonomer
prepared above.

[0122]A 5-liter flask was equipped as in Example 1. The flask was held
under nitrogen positive pressure and the following ingredients were
employed.

[0123]Portion 1 mixture was charged to the flask and the mixture was
heated to reflux temperature and refluxed for about 10 minutes. Portion 2
was added over 3 hours and Portion 3 was simultaneously added over 3.5
hours while the reaction mixture was held at reflux temperature. The
reaction mixture was refluxed for another 1.5 hours.

[0124]After cooling, the resulting macromonomer solution was a clear
polymer solution and had a solid content of about 51.3% and a
Gardner-Holtz viscosity of Y+1/2. The macromonomer had a 20,027 Mw and
8,578 Mn after the carboxyl groups were protected by methyl groups to
facilitate the GPC analysis.

Example 3

Preparation of an ABA' Triblock Copolymer

[0125]This example shows the preparation of an ABA' triblock copolymer of
this invention containing carboxyl groups, and primary hydroxyl groups on
both the A

[0128]Portion 1 mixture was charged to the flask and the mixture was
heated to reflux temperature and refluxed for about 10 minutes. Portion 2
and 3 were simultaneously added over 3 hours while the reaction mixture
was held at reflux temperature. The reaction mixture was refluxed for 30
minutes. Portion 4 was added over 5 minutes, and the reaction mixture was
refluxed for another 2 hours. Portion 5 was added toward the end of the
reflux.

[0129]After cooling, the resulting ABA' triblock copolymer solution was
slightly hazy and had a solid content of about 50.2% and a Gardner-Holtz
viscosity of Z1. The triblock copolymer had a relatively narrow
distribution of molecular weight with 28,146 Mw and 12,176 Mn, and a very
high Tg of 110C measured by Differential Scanning calorimetry.

[0132]Portion 1 mixture was charged to the flask and the mixture was
heated to reflux temperature and refluxed for about 10 minutes. Portion 2
and 3 were simultaneously added over 3 hours while the reaction mixture
was held at reflux temperature. The reaction mixture was refluxed for 30
minutes. Portion 4 was added over 5 minutes, and the reaction mixture was
refluxed for another 30 minutes. Portion 5 was added over 5 minutes and
the reaction mixture was refluxed for 2 hours. After cooling, the
resulting triblock copolymer solution was slightly hazy and had a solid
content of about 47.5% and a Gardner-Holtz viscosity of Z+1/2. The
triblock copolymer had a 30,291 Mw and 13,288 Mn, and a Tg of 84.6 C
measured by Differential Scanning calorimetry.

[0135]The procedure of Example 4 was repeated. After cooling, the
resulting ABA' triblock copolymer solution was slightly hazy and had a
solid content of about 51.5% and a Gardner-Holtz viscosity of Z1. The
triblock copolymer had a relatively narrow distribution of molecular
weight with 29,472 Mw and 13,063 Mn, and a very high Tg of 110C measured
by Differential Scanning calorimetry.

Example 6

Preparation of an ABA' Triblock Copolymer

[0136]This example shows the preparation of an ABA' triblock copolymer of
this invention containing carboxyl groups, primary hydroxyl groups, and
polyethylene oxide groups on one terminal block and the primary hydroxyl
groups only on the other, no specific functional groups on the center B
block, specifically methyl methacrylate-co-butyl
methacrylate-co-2-hydroxyethyl methacrylate-b-butyl
methacrylate-co-methyl methacrylate-b-methacrylic acid-co-hydroxyethyl
methacrylate-co-ethoxytriethyleneglycol methacrylate,
34/23/81115.75/10.5115.25/1.75/1.75% by weight, from a macromonomer
prepared above.

[0137]A 5-liter flask was equipped as in Example 1. The flask was held
under nitrogen positive pressure and the following ingredients were
employed.

[0138]Portion 1 mixture was charged to the flask and the mixture was
heated to reflux temperature and refluxed for about 10 minutes. Portion 2
and 3 were simultaneously added over 3 hours while the reaction mixture
was held at reflux temperature. The reaction mixture was refluxed for 30
minutes. Portion 4 was added over 5 minutes, and the reaction mixture was
refluxed for another 2 hours.

[0139]After cooling, the resulting ABA' triblock copolymer solution was
slightly hazy and had a solid content of about 47.1% and a Gardner-Holtz
viscosity of Y. The triblock copolymer had a relatively narrow
distribution of molecular weight with 28,679 Mw and 12,546 Mn, and a very
high Tg of 76.8 C measured by Differential Scanning calorimetry.

PAINT EXAMPLES

Paint Examples BC2 to 5, BC7 to 0 and Comparative Examples BC1, BC6

[0140]The following air-drying lacquer basecoats were prepared from the
following pre-blends and then tested.

[0141]The following pre-blends were made on an air mixer, adding the
cellulose acetate butyrate, if employed, slowly with vigorous mixing:

[0142]The ingredients were blended together on an air mixer (basecoats BC2
to BC5 use triblock acrylic copolymers of Example 3 to 6 as gram for gram
solid replacements for the solid CAB in the comparative Example BC1 while
BC7 to BC10 replace both the CAB and the conventional random acrylic
resin in the comparative Example BC1 with the triblock acrylic copolymers
of Example 3 to 6 on a solid gram for gram basis) to form the silver
metallic basecoats BC1 to BC10:

[0143]The silver basecoats were sprayed per the application instructions
used for DuPont® ChromaPremier® Basecoat specified in the DuPont
ChromaSystem Tech Manual. The basecoats were sprayed to hiding over Ecoat
panels (ACT cold rolled steel 04×12×032 panels coated with
Powercron 590) which were scuffed with a 3M® Scotch-Brite® 7777
Imperial® Paint Prep Scuff Pad then wiped with DuPont First Klean
3900S® and next coated with DuPont® ChromaPremier®
42440®/42475S® 2K Premier Sealer as per the instructions in the
DuPont ChromaSystem Tech Manual.

[0144]The basecoats were then clearcoated with DuPont® ChromaClear®
V-7500S® Multi-Use as per the instructions in the DuPont ChromaSystem
Tech Manual. Basecoat/clearcoat panels were flashed and then baked in a
140° F. oven for 30 minutes. Topcoated panels were allowed to air
dry for an additional 7 days prior to testing.

[0146]None of the triblock copolymers performed as well for color using a
gram for gram replacement for CAB. However, when the triblock acrylic
copolymers of this invention were used as the main component of the
binder in the absence of CAB (BC7 to 10), these panels gave color very
comparable to that of the Comparative Example BC1 with CAB. It was also
clear that the conventional random acrylic resin as a main binder
component in the Comparative Example BC6 did not fair well for color
(especially flop) vs. the Comparative Example BC1 containing CAB.

[0147]Below are the color readings on basecoat/clearcoat panels recorded
by the same instrument:

[0148]Below are the color readings comparing the color of the basecoat
alone panels vs. those of the basecoat/clearcoat (the delta of basecoat
alone readings minus the basecoat/clearcoat readings indicates the
approximate amount of strike-in caused by clearcoating the panels):

[0149]In addition to the observations made on the basecoat alone panels,
the delta readings indicate that none of the triblock copolymers as a
gram for gram replacement for CAB provided the strike-in resistance of
CAB (BC1 with CAB vs. BC2 to BC5). However, when the triblock copolymers
of this invention were present as the main binder component in the
absence of CAB (BC7 to BC10), the strike-in resistance was comparable to
that of the basecoat containing CAB (BC1). Again, when the conventional
random acrylic resin was the main binder component without CAB (BC6), the
strike-in resistance was very poor.

[0150]The tables below show the results of "Dry Chip" gravelometer testing
per ASTM-D-3170-87 using a 55 degree panel angle, with panels and stones
kept in the freezer for a minimum of two hours prior to chipping. Each
basecoat/clearcoat shows a rating and locus of failure using 1 pint or 3
pints of stones. The results of "Wet Chip" gravelometer testing per
ASTM-D-3170-87 using a 55 degree panel angle, with panels and stones kept
in the freezer for a minimum of two hours prior to chipping, are also
included. For the "wet chip" gravelometer testing the panels were exposed
in a humidity cabinet per ASTM-D-2247-92 at 100% relative humidity for 96
hours after they were air dried for 7 days after the 140°
F.×30 minute bake.

[0152]Use of the triblock copolymers of Example 3 to 6 of this invention
in BC7 to BC10 eliminated the clearcoat delamination seen when using the
conventional random acrylic copolymer alone in the Comparative Example
BC6.

[0154]The Comparative Example BC1 containing CAB displayed severe
clearcoat delamination while none of the basecoats having the replacement
resins of this invention BC2 through BC5 and BC7 through BC10 on a gram
for gram solid replacement basis for CAB or a total replacement of CAB
and the conventional random acrylic resin did.

[0155]Various modifications, alterations, additions or substitutions of
the compositions and processes of this invention will be apparent to
those skilled in the art without departing from the spirit and scope of
this invention. This invention is not limited by the illustrative
embodiments set forth herein, but rather is defined by the following
claims.